Last week Microsoft started deploying its October 2018 update (called version 1809) for its Windows 10 operating system. Since then there have been reports of people losing some or all their personal files during the upgrade process. Here is a good summary of the issue from Engadget:
https://www.engadget.com/2018/10/05/windows-10-october-update-1809-delete-data-wipe-user-profile/
That article describes a tool and a setting normally not used or needed except in large corporations or universities. I don't recommend messing with it unless you really know what you are doing.
Since the initial publication of the error it appears that Microsoft has stopped further distribution of the update until they can resolve the issue. Here is a summary from Bleeping Computer about the pulling of the update:
I had successfully updated several Patricia Egen Consulting computers before the update was pulled. I will postpone any further updates until Microsoft resolves the issue. In the meantime here are my current conclusions and recommendations:
- If you have already successfully updated to version 1809 I see no good reason to fall back.
- If you have not installed the update, sit tight and let Microsoft resolve the issue and publish their corrected update or other workaround.
- If you are running Windows 10 Pro or Enterprise you can enable a setting to defer the update for some period of time as described in this ZDNet article. https://www.zdnet.com/article/windows-10-spring-creators-update-act-fast-to-delay-this-big-upgrade/ This may save you a surprise when Microsoft chooses to reenable distribution of the update. Unfortunately there is no corresponding setting for Windows 10 Home.
- In any case your best protection is a good backup of all your files that you care about, somewhere off the machine in question. This could be an external hard drive, a space on a file server, or one of any Cloud backup solutions, as long as it is something you use consistently.
Hope this helps.